Cover closing mechanism for centrifugal machines



COVER CLOSING MECHANISM FOR CENTRIFUGAL MACHINES Filed Nov. 2, 1949 2Sheets-Sheet 1 fol/ecs- ATTORNEY April 19, 1955 c. A. OLCOTT 2,706,561

COVER CLOSING MECHANISM FOR CENTRIFUGAL MACHINES Filed Nov. 2, 1949' 2Sheets-Sheet 2 AIR J'OUPCE' .INVENTOR. (#421 if 4. 0L 6077' UnitedStates Patent COVER CLOSING MECHANISM FOR CENTRIFUGAL MACHINES CharlesA. Olcott, West Milford, N. J.

Application November 2, 1949, Serial No. 125,041

2 Claims. (Cl. 210-63) This invention relates to centrifugal machinesand more specifically to an automatic cover closing mechanism for amachine of that type.

It is an object of this invention to simplify automatic cover closingmechanisms for sugar centrifugal machines and to improve theiroperation.

Patent 2,254,388 issued September 2, 1941 to C. A. Olcott discloses acover closing mechanism for a sugar centrifugal machine. The machineincludes a curb enclosing a centrifugal basket, a cover for the curb,and an automatic mechanism for closing the cover in response to themovement of appropriate centrifugal controls to their positionscorresponding to the high speed running of the centrifugal and foropening the cover in response to the movement of such controls topositions corresponding to the condition where the centrifugal basket isat rest. The basket is thus closed during the time when it is importantthat the heat and moisture be retained therein, to facilitate purgingand washing, and is opened for suitable access for discharging the sugarand loading it with a new charge of massecuite. The arrangementdisclosed in the patent includes for operating the cover (actually it isa pair of covers) an air cylinder, a retrieving spring and a series ofair pressure and solenoid valves, the solenoid valves being operated byappropriate electrical connections which are energized or deenergizedcorresponding to the running and the at-rest condition of thecentrifugal basket.

Cover operating mechanisms of the general type just described have beenput into use and a number of benefits are claimed for them by theoperators. Among these benefits are the following:

(1) It is possible to reduce the amount of wash water used to wash thesugar in the centrifugal because when the heat is retained and the airis excluded a smaller amount of wash Water is suificient to properlyclean the crystals. This reduction in the amount of wash waterautomatically applied is not a safe operation to follow unless thecovers are automatically operated because if the operator should neglectat times to close the covers, then the amount of wash water, which hasbeen automatically predetermined to conform to the closed condition ofthe curb, is not sufiicient to clean the crystals when the cover is leftopen, as frequently occurs due to negligence on the part of theoperator, and this improperly washed sugar has a very poor quality, andif mixed with other sugar, lowers the quality of the entire mass ofsugar being treated in the refinery. Therefore, in operation, as amatter of safety the predetermined amount of wash water is made largeenough to insure reasonably satisfactory washing even if the cover mayat times not be closed and, of course, such an amount of water is muchmore than is necessary when the cover is closed with the result thatgood sugar is lost and must be re-processed at additional cost.

(2) It prevents secondary charging. It has been found that when a fullcharge of massecuite has been introduced into the basket and thecentrifugal speeded up, with the resultant throwing off of the molassesfrom the basket, the volume of material in the basket is reduced leavinga space into which the operator can put additional massecuite to fill upthe basket again, and the operators like to do this because it helpsthem to centrifuge more sugar with less work. However, this practice isvery bad because it causes green molasses to flow through a mass ofsugar crystals which have already been partly purged, with the resultthat the entire mass of sugar is unsatisfactorily purged of its greensyrup and the wash water is less effective and this results in theproduction of sugar which is high in ash content and otherwise low inquality. This secondary charging is apt to take place when the coversare not automatically operated because the operator will not close thecovers until he has put in his second and perhaps a third charge ofmassecuite. The managing personnel of sugar factories who are acquaintedwith this condition endeavor to order the operators not to engage insecondary charging, but their orders have little effect because theoperators can reduce the amount of manual labor by following this badpractice and therefore tend to follow it as soon as the foremans back isturned. When the covers are automatically operated, then, when themachine picks up speed and the molasses is thrown out of the basket,leaving a space in which more massecuite can be charged, the covers areclosed preventing the addition of more massecuite and forcing theoperator to operate the machines in accordance with the instructions oftheir employers.

(3) The use of automatically operated covers contributes substantiallyto the safety of operation of these sugar drying centrifugals. Theunloading device commonly used on centrifugals is designed to plow outthe sugar while the basket is rotating at low speed and sometimes whenan operator has become tired after working for several hours he maythink that the machine has come to a stop when actually it may berunning at high speed (but so smoothly that no motion is visible) and itall too frequently happens that he will attempt to plow out the sugar byintroducing the plow into the running machine with resultant breakagesof parts of the unloading device and perhaps of the centrifugal itselfand even in some cases serious physical injury to the operator; but theautomatically operated cover mechanism prevents these accidents becausewhen the cover is closed (which is its position when the machine isrunning at high speed), the operator cannot move the unloader into aposition where the plow engages the sugar in the massecuite because thecovers, closing as they do the basket and curb, prevent any suchmovement.

It is thus clear that these covers contribute substantially to thesafety and efliciency of operation of sugar drying centrifugals. Whilethe arrangement described in the above-identified Olcott patent can beapplied to practically any type or design of sugar centrifugal, it hasbeen found that a substantial reduction in the amount of equipmentrequired (and hence in the cost of the equipment and in the maintenancethereof) can be achieved when these covers are installed on centrifugalswhich are automatically controlled by an automatic controller of thepneumatic type and, moreover, an improvement in operation results.

It is, accordingly, another object of this invention to reduce theexpense of operation and of maintenance of centrifugal cover closingmechanisms in centrifugals operated by automatic controllers.

It is a further object of this invention to improve the operation ofcentrifugals with automatically controlled covers.

The above and related objects areattained in accordance with anexemplary embodiment of the invention by interlocking, in a sugarcentrifugal machine, the operation of the automatic cover closingmechanism -with that of the automatic controller used to time theoperations of the centrifugal basket. The automatic controller is of thetype which makes use of compressed air and may be, by way of example,the device known as the Steps Master Centrifugal Control manufactured bySugar Machinery Co. of Los Angeles, Calif, and which is described inSteps Patent 1,947,679 issued February 20, 1934. This automaticallycontrolled device is widely used in the sugar industry and controls theoperations of the centrifugal. By making use of this type of controllerwith the coveroperating mechanism of the Olcott patent, it is possibleto eliminate a solenoid valve and its related equipment used in thepatented Olcott device as well as improve the operation of thecentrifugal in some cases, as will be described more fully below after adetailed description of the invention.

The invention will be more readily understood by eferring to thefollowing description taken in connec ion with the accompanying drawingsforming a part hereof, in which:

Fig. 1 shows, partly in plan and partly in circuit chematic form, anautomatic cover-closing mechanism :1 accordance with the invention; and

Fig. 2 is a front elevation of a centrifugal, partly n section,including the top covers and part of the tctuating mechanism shown inFig. l.

Referring more specifically to the drawings, Flgs. l and 2 show, by wayof example for purposes of il- .ustration, an automatic cover closingmechanism :onstructed in accordance with the invention for a sugarcentrifugal machine 11. The machine 11 in- :ludes a fixed casing 12enclosing a centrifugal basket 13 suspended therein and rotated througha shaft 14 by a motor 15. The motor is supported by a superstructure,not shown, from which the shaft 14 and the basket 13 are suspended sothat the centrifugal may ro tate freely within its casing 12. Two topcovers 16 and 17 employed for closing the top opening of the centrifugaland all of the cooperating mechanism are shown in the closed position inFig. 2 and in the fulllines in Fig. l, and these are shown in the openposition in the dotted lines in Fig. 1. The closed position correspondsto the high speed running condition of the centrifugal while the openposition corresponds to the period after the normal running cycle hasbeen completed to make the basket 13 accessible for the discharging andcharging operations performed while the machine is at rest or turning atlow speed. The covers are opened and closed by a group of levers andarms (which will be described below) controlled by an air pressurecylinder 18 and a spring 19 both an chored to a base plate 28. Thepiston in the cylinder 18 is operated by compressed air from a source 21which is connected to the cylinder 18 by means of a pipe 22, a three-wayvalve 23 of any well-known type, and pipes 24 and 25. By way of example,a suitable valve is shown in Fig. 3 of the above-identified Stepspatent. A pipe 26 vents air from the valve 23 at the desired ventingtimes. The air source 21 is also connected to the pipe 24 through thepipe 22 and valve 23 and is connected through the pipe 24 and the Tjoint 27 to a timing cabinet controller 28 for centrifugals which is ofany suitable type which operates in response to admission of airpressure to the timing cabinet. By way of example, it can be of the typefully shown and described in the above-identified Steps patent so thedetails of the be repeated at this point. By means of a pipe 29 to anair pressure cylinder 30 the brakes 31 are applied at the proper time ineach cycle of operation.

Before describing the operation of the pneumatic equipment brieflymentioned above, details of the cover operating lever mechanism willfirst be given. Cover 17 swings on bar lever 40 from a pivot 41 in plate42, the lever 40 being attached to a fiat plate 43 which is bolted tothe cover 17 and which is attached by means of coupling 44 to the rod 45fastened to the piston in the air cylinder 18. When the rod 45 isactuated to the right by air cylinder 18, the cover 17 is rotated as aunit with bar 40 in a horizontal plane about the pivot 41 to its extremeright hand position (the full-line position in Fig. 1) sliding over thetop surface of the casing 12 to close the left hand portion of thecircular opening 32 in the casing. Movement of the bar 40 also controlsthe operation of cover 16 simultaneously with the actuation of cover 17.Cover 16 is actuated to close the right hand portion of the circularopening 32 in the following manner. As bar 40 is actuated to the rightit moves a bar 46 which is pivoted to the bar through pin 47. The bar 46is pivoted in turn through pin 48 to the upper end of a bell crank lever49. The latter is pivoted through a pin 50 which is rigidly fixed in thetop of casing 12. At its lower end, bell crank lever 49 is bolted bymeans of bolts 51 to the right hand cover 16. As bar 46 is actuated tothe right, it rotates the upper end of the bell crank lever 49 to theright about its pivot pin 50 in turn operating cover 16 toward the left.The cover 16 slides also in a horizontal plane over the top surface ofthe casing 12 to close the right hand portion of the circular opening32. Two flat bars 52 and 53 are bolted to the cover 16. These bars serveto cover any opening which timing cabinet 28 need not 86 ing said airsupplying means may exist in the joint between adjacent edges of thecovers 16 and 17 when they are closed. The covers 16 and 17 togetherwith the bars 52 and 53 effectively cover the top opening 32 in thecasing 12 and substantially prevent the flow of air through the topopening. For a more detailed description of top cover linkage mechanismsof the type briefly described above reference is made to theabove-identified Olcott patent.

The operation of the arrangement shown in Figs. 1 and 2 will now bedescribed. Assume that the covers 16 and 17 are open and the basket 13in the centrifugal machine 11 has just been charged. The valve 23 isthen manually turned by the operator to the On position to admitcompressed air from the source 21 to the cylinder 18 by way of pipe 22,valve 23 and pipes 24 and 25 to actuate rod 45 to the right to close thecovers 16 and 17 and at the same time to admit air to the controllercabinet 28 at the time when the power is turned on to accelerate themachine to full speed so that the sugar can be purged, washed and dried.All of these latter operations are automatically timed by the equipmentin the cabinet 28 according to the periods of time adjusted by thesetting of the dials 54, 55, 56 and 57. As fully set forth in thedisclosure of the above-identified Steps patent, the automatic equipmentin cabinet 28 times all functions up to and including the application ofthe airoperated brake 31 which stops the centrifugal 11. Thus, when theoperator returns to the machine which has been under the control of thetiming equipment in the cabinet 28 up to the end of its running cycle,he finds the machine stopped with the air brake 31 set by reason of airadmitted to the cylinder 30 and the basket 13 holds sugar which has beenpurged, washed and dried. To discharge the sugar from the basket theoperator must release the brake 31 which he does by moving the handle ofthe valve 23 to the OE position. This shuts off pressure from the source21 permitting the air pressure in the pipe 24 to be exhausted to theatmosphere through pipe 26 and thus has the effect of permitting all ofthe timers applying to the particular centrifugal 11 to return to zeroand also to vent the cylinder 18 allowing the spring 19 to move the bar40 to the left opening the covers 16 and 17. In the zero position of thetimers in the control cabinet 28 of the Steps type, a three way valvecontrolled by the timing gears set by one of the dials 54 to 57,inclusive, cuts off air pressure from brake cylinder 30 and vents thiscylinder to the atmosphere through the cabinet 28.

It will be noted that in combining the operation of the Steps controllerwith the cover closing mechanism described in the Olcott patent, thesolenoid valve, the centrifugal switch and various electricalconnections used in the patented Olcott device are not necessary. Thebenefits are substantially the same but in coordinating the opening andclosing of the covers in a manner in which they are responsive to manualoperations normally performed at the proper times, the amount ofequipment necessary to control the covers is substantially reduced. Thisnaturally makes the covers and their operating equip ment less expensiveto manufacture and install and also reduces the amount of equipmentwhich has to be maintained. Another advantage of the present arrangementis that the operation is improved in all cases where it is desirable tohave the covers closed during deceleration of the centrifugal (which isnot the case in the arrangement covered in the Olcott patent).

While the Steps control arrangement is described herein by way ofexample as a satisfactory controller, it should be clearly understoodthat any other suitable pneumatic controller can be used instead.Moreover, the present invention is not limited to the use of the exactcover operating linkages described in the Olcott patent.

Various other changes can be made in the embodiment described above,without departing from the spirit or scope of the invention as indicatedby the claims.

What is claimed is:

1. A sugar centrifugal machine comprising a curb having an openingtherein, a basket within said curb, means for rotating said basket, abrake for said machine, a cover for the curb, a cylinder having a pistontherein operative between two positions at which the cover isrespectively open and closed, automatic timer means to apply wash waterto said basket and to apply said brake at predetermined times after thetimer means is energized, means for supplying high pressure air, meansfor connect to said automatic timer means and to said cylinder, andmeans including a single pneumatic valve in said connecting means forsimultaneously starting the energization of said timer means and themovement of said piston to the cover closing position and forsimultaneously controlling the deenergization of said timer means andthe movement of said piston to the cover opening position.

2. A sugar centrifugal machine comprising a curb having an openingtherein, a basket within said curb, means for rotating said basket, abrake for said machine, a cover for the curb, a cylinder having a pistontherein operative between two positions at which the cover isrespectively open and closed, automatic timer means to apply wash waterto said basket and to apply said brake at predetermined times after thetimer means is energized, means for supplying high pressure air, meansfor connecting said air supplying means to said automatic timer meansand to said cylinder, and means including a single pneumatic valve insaid connecting means for simultaneously starting the energization ofsaid timer means and the movement of said piston to the cover closingposition and for simultaneously controlling the deenergization of saidtimer means and the movement of said piston to the cover openingposition, said valve being of the three-port, two-position type andhaving one of its ports connected to said source, a second of its portsconnected to said timer and to said cylinder, and the third of its portsconnected to a vent.

References Cited in the file of this patent UNITED STATES PATENTS1,947,679 Steps Feb. 20, 1934 2,254,388 Olcott Sept. 2, 1941 2,325,406Johnson July 27, 1943 2,328,394 Ncuman Aug. 31, 1943 2,521,054 EllisSept. 5, 1950

